In each of the questions given below four words are given in bold. These four words may or may not be in their correct position. The sentence is then followed by options with the correct combination of words that should replace each other in order to make the sentence grammatically and contextually correct. Find the correct combination of the words that should interchange. If the sentence is correct as it is then, select option “No interchange required” as your choice.

The primitive mirror (A) society was built to virtual (B) the carefree state of lived (C) that people once nature (D) in.

To determine the correct combination of words to interchange, let us analyze the grammar and context of the given sentence step-by-step.

The original sentence is:
"The primitive mirror (A) society was built to virtual (B) the carefree state of lived (C) that people once nature (D) in."

Step 1: Analyze position (A) and (B)
The phrase "primitive mirror (A) society" is contextually awkward. More importantly, the phrase "built to virtual (B) the..." requires a verb after the infinitive marker "to". "Virtual" is an adjective, whereas "mirror" can act as a verb meaning to reflect or copy. If we interchange A (mirror) and B (virtual), we get:
"...primitive virtual (B) society was built to mirror (A) the carefree state..."
Here, "virtual" correctly modifies "society" as an adjective, and "mirror" acts as the required verb in "to mirror". This swap is grammatically and contextually correct.

Step 2: Analyze position (C) and (D)
The phrase "carefree state of lived (C)" is grammatically incorrect because "of" (preposition) should be followed by a noun phrase or gerund, not the past tense verb "lived". Looking at the end of the sentence, "that people once nature (D) in" is also grammatically incorrect because "nature" is a noun, but the sentence requires a verb here to describe what people did "in" that state. If we interchange C (lived) and D (nature), we get:
"...carefree state of nature (D) that people once lived (C) in."
Here, "state of nature" is a well-known philosophical and contextual concept, and "lived in" is a grammatically correct verb-preposition combination ending the relative clause.

Step 3: Combine the interchanges
Combining both correct interchanges, the sentence becomes:
"The primitive virtual (B) society was built to mirror (A) the carefree state of nature (D) that people once lived (C) in."
This sentence is both grammatically correct and contextually meaningful.

Therefore, the words at A and B must interchange, and the words at C and D must interchange. This corresponds to the combination A-B & C-D.